CUT50 board connections?

[skotl]

I'm with Gaz on this one. The dust could be conductive and may have caused the problems but, that aside, it would be better to run a hoover over it and clean up the board so we can better see what's happening.

C15 looks dreadfully unhappy...

only used it 3 times before it went pop!

Yep - mine was only used a handful of times before it went up, too!

 

[stonkin9899]

Thanks for the replies. Here is a picture of the board causing the issues. When unplugged I get the fans running. But something has shorted as when plugged in it totally dies I've removed 1 component to test q13 the k2611

 

[stonkin9899]

the capacitor has been replaced as it had exploded (circled) component removed circled, unhappy component marked

 

[gaz1]

so thats the top board then





and you have removed the transistor
it will have taken something else out with it as it always does

can you take a pic of the board underneath as your looking for burn marks or destroyed copper lines its also one photo not many post up either

 

[stonkin9899]

The transistor seems to be okay, I've put it back in

 

[stonkin9899]

one other thing i've noticed on this same board, the connector to it, 3 red 3 black are reversed. red is negative and black is positive... is this right?

 

[gaz1]

check d1 infront of the transistor as well

please try getting clearer unedited photos it helps to zoom in on them

underneath the board looks fine thanks for posting that up

 

[stonkin9899]

Anyone got a wiring diagram, defo looks like i've got a short somewhere, but cannot understand where, D1 seems fine, thanks for the help so far!

 

[stonkin9899]

So i've taken the transistors off and found 5 so far testing bad (i have a little component tester) so ill replace them, but also want to replace the pictured blown cap, anyone know the value of C15?

 

[typex240]

So I bought a cut50 and right out of the box I plugged it in turned it on and had three loud pops and then nothing. When I opened it it up I found that the bar running from front to back was bent and touching the board. Also two of the capacitors had blown and a large trace right off the ac input blew. I replaced the capacitors and repaired the trace. Then plugged it back in. Turned it on and one loud bang. The trace blew again. Any info into the repair of this would be greatly appreciated. I did disconnect the 220 plug to make it easier to handle for the moment. It was wired correctly to the ground strap and the switch.

 

[gaz1]

typex your board is not a cut50 might be a newer model, yes it still can be a cut 50 though

but it is not the cut50 machine on this post as they are a split board unit

 

[skotl]

(welcome to the forum for reference, it's probably best to start a new thread rather than resurrect an old one)

Is there any chance of a better pic of the circuit board with the scorch marks? It's difficult to tell what it is, but it looks fubar'd to be honest.
Probably too late now but, if you'd just bought it then the best option should have been to return it.

Anyways - it's not a complex board so I'd be testing components one by one (lifting one leg or removing each component entirely, to test discretely).

 

[typex240]

Any idea why it would blow the main trace on the ac input and nothing else. I know my 220 at the box is wired correctly because I just got done cutting up a suv with my friends cut 50. And it did awesome.

 

[skotl]

Any idea why it would blow the main trace on the ac input and nothing else. I know my 220 at the box is wired correctly because I just got done cutting up a suv with my friends cut 50. And it did awesome.

Not sure what you mean by "main trace". Do you mean the track on the PCB?

If so, then that's a very unusual (and catastrophic) type of failure. Fuses and MCBs are supposed to blow/trip long before this kind of damage is caused.
It's going to be a dead short (or something very close to it) on the PCB but I'd be wondering why your fuse wasn't blowing first.

If it's not the PCB track then a pic of what you're referring to would be helpful.

 

[typex240]

Yes it's the pcb track. Sorry always called it a trace. Yeah didn't blow a fuse or anything just the track and its a wide one right off the ac in I'll remove the piece in the way this evening and send a better picture.

 

[R Kraft]

I would try to test the main bridge diode first.

 

[typex240]

So I am somewhat of a newbie on circuit boards. I am a mechanic by trade but have dabbled with electronics for the past few years. All self taught. I've repaired big screens old and newer. Done hundreds of Xbox 360 board repairs. Some cell phone stuff and amplifiers. So bear with me.

Here is a better picture of the board. I removed the capacitor next to it and whatever this is next to the blown track.

 

[typex240]

And I cleaned it before the pic if that wasn't apparent. Lol.

 

[eddie49]

The 220v AC mains input will connect to a bridge rectifier, possibly via a mains filter. The rectifier may be under the small rectangular heatsink. There will be a soft-start circuit using a resistor or thermistor bypassed by a relay after a delay to allow the four large capacitors to charge. The smoothed output of the rectifier will be 310v DC, and this will connect to the inverter section, where the multiple MOSFET or IGBT power transistors turn it to high frequency AC.
As R Kraft said, the rectifier may have shorted, or one or more of the power transistors may have been damaged by the initial problem with the metal bar.
If you locate faulty ( short- or open-circuit ) power transistors, it is important to note that the gate driver circuits may have suffered consequential damage, so it is vital to verify them before fitting new transistors. When the power transistors blow they often conduct high voltages through to the gate, damaging the gate driver circuitry, therefore you need to investigate and check the components on each gate before risking new transistors.

 

[eddie49]

The rectangular component with one slant-cut corner is the bridge rectifier. It contains 4 diodes. You can check it with a multimeter on the Diode Test range. There is a test procedure in Post #31 of this thread:

Testing diodes

Yesterday I was welding up some large axel stands for use in a 4 post lift Welded up the bases on full power (7-180amps), welded fine then all of a sudden it's as if the power settings had been turned down but it obviously wasn't It's done this when I first bought it but I thought it might...

www.mig-welding.co.uk

The burnt track is one of the two AC inputs to the rectifier. The copper is melting because the rectifier is shorted, or because the load on the output side of the rectifier is too high, which could be due to shorted capacitors or power transistors.